As energy costs and the need for tighter control of costs increase, the unauthorized use of gas creates mounting concern. Energy companies, in an effort to reduce this unauthorized use, have investigated possible solutions. Efforts have been made to determine the type of fuel burned from the emissions of the combustion. Typically, the plume of emissions emanating from a stack would be sampled. In order to sample these emissions, access to the stack is necessary. The samples taken are then analyzed to determine the type of fuel used. In most situations, the taking of samples is difficult due to the inaccessibility from the ground of stack emissions. This inaccessibility is sometimes exacerbated by uncooperative building owners or tenants.
It became necessary for energy companies to seek alternative solutions to their unauthorized gas use problems. Lasers could be used to remotely sense chemical compounds in the stack emissions. Laser systems tend to be complex and therefore costly. Additionally, laser systems, not being passive, result in health risks and potential injury from laser light. These remote detectors also tend to be unreliable and produce a high false alarm rate, a false alarm being an erroneous indication of gas combustion when in actuality none existed.
While the apparatus and methods used to distinguish between the combustion of oil and gas fuels have assisted energy companies somewhat in reducing the unauthorized use of gas, none could adequately identify gas combustion easily. Therefore, it became necessary to investigate other apparatus and methods for distinguishing between gas and oil combustion.